The invention relates to a greenhouse according to the preamble of claim 1, which is particularly suited for northern conditions wherein growing requires both artificial light and additional heating.
Energy costs represent an extremely large item of expenditure in greenhouse cultivation. For instance in 2000 to 2006, electricity costs almost doubled and fuel costs increased approximately 40%. Further, energy production utilizes large amounts of fossil fuels for which saving goals relating to environmental protection exist.
The temperature at latitudes north is highly significantly lower than at latitudes south. The existing basic models of greenhouses are mainly designed for southern conditions and are thus often poorly suited for our cold conditions. The energy consumption of greenhouses is extremely high in winter since glass roofs and walls of the greenhouses that receive the smallest amount of sunlight are poorly thermally insulated. On the other hand, in the summer the problem with the existing greenhouses is that owing to the long days the thermal load tends to become even too heavy.
An attempt has been made to partially solve these problems e.g. by structural procedures according to patent publication GB 2215357. Admittedly, such a greenhouse according to the publication has been insulated better than before but, on the other hand, these structural solutions result in the greenhouse having to be provided with additional lighting in order for the total luminous efficiency required by the plants to be achieved under all conditions.
The above-mentioned patent publication also discloses movable and reflecting element solutions to be placed outside a building. However, the structural and functional solutions of such elements are not at all usable in the ice and snow conditions of the northern winter.